SUBSURFACE AND PETROLEUM GEOLOGY OF ASHTABULA COUNTY, OHIO A Thesis Presented in Partial Fulfillment of the Requirements For the Degree Bachelor of Science by James W. Shoots The Ohio State University 1985 Approved by : A visor Department of Geology and Mineralogy CONTENTS ~ Introduction 1 The Precambrian Surface 3 The Cambrian Period 8 Ordovician and the Tippecanoe Sequence 12 The Lower Silurian and the Grimsqy Sandstone 14 Middle and Upper Silurian 19 Devonian Carbonates and Shales 22 Lower Mississippian Outcrop 26 Summary and Conclusions 28 Bibliography 29 INTRODUCTION Ashtabula County, Ohio is located in the very northeastern corner of the state (fig. 1). Its geographical boundaries include: Lake Erie to the north; Crawford and Erie Counties, Pennsylvania to the east; Trumbull County, Ohio to the south; and Geauga and Lake Counties to the west. All these surrounding areas were helpful in correlating well data to make inferences to trends that underlie Ashtabula County. The study area is located on the northwestern flank of the Appala­ chian Basin. This basin is an elongate structural trough trending northeast-southwest. It stretches from New York to Alabama. Cambrian seas deposited large sections of carbonates in a depression that developed on the Precambrian surface (ref. 9, p. 17). The Taconic orogeny of Late Ordovician time filled the basin with large quantities of clastic mater­ ial from the east and southeast. Again, in Middle Devonian time, new uplift, accompanying the Acadian Orogeny, deposited masses of marine and terrestrial materials in the same subsiding basin. A continuing orogeny, throughout the late Paleozoic, culminated in the Appalachian orogeny which occurred near the close of the Paleozoic (ref. 9, p. 17). At this time, the eastern flank of the Appalachian Basin was intensely folded, faulted, overthrust, and intruded by igneous bodies. The western flank, however, remained little deformed (ref. ~' p. 3.~). To the west and northwest of the study area, the Cincinnati, Findlay, and Algonquin Arches are found. In general, these arches separate the Appalachian Basin from the Michigan and Illinois Basins. Structural development of these arches began during the Ordovician time and remained positive features until Late Pennsylvanian time. 1 2 \ I -----j,6,.,---J ~ ....... 1""'"-·" ! \ ) I 7 ,.,,.;;c__~ i ('"" '' rmor- _r, -c! Ro=- · L , I I l -"':'···---- _j I ,.,.,.- -----,_1 i L I L- I I I .--j I I ' / L__ L____,__! --'=1 l ;-· '------'~!_ ,_, i.__l~ '---"---~ /--__/ ~· ~ Figure t. AREA OF SWDY - 3 THE PRECAMBRIAN SURFACE In 1890, Edward Orton, Sr., third State Geologist of Ohio suggested that, "If we should descend deep enough below the surface, we should reach the limit of these stratified deposits and come to the great foundations which constitute the surface rocks in parts of Canada, New England, and the West. The granite of Plymouth Rock underlies the continent." In 1912, this hypothesis was seem­ ingly confirmed by a well penetrating granite rocks in Hancock County, Ohio. A total of 138 wells have now been drilled into the crystalline basement rocks in Ohio. Eight of these wells were drilled in Ash­ tabula County (fig. 2). They are not all similar to Plymouth Rock, but highly variable. These Precambrian age rocks are estimated to have reached their present form between 1.5 to 0.8 billion years ago. Their depths range from 3000 feet in western Ohio to 12,000 feet and more in eastern Ohio. In Ashtabula County, they are found at depths of approximately 7000 to 7500 feet. The Precambrian surface is known not to be a smooth, level one, but one that underwent consider­ able erosion before it was buried by Paleozoic sediments of the Cam­ brian Period. From the deep wells drilled in Ohio, it can be concluded that Precambrian rocks east of west-central Ohio are in general metamorphic rocks with radiometric ages of 0.8 to 1.1 billion years. In western Ohio, they are in general, igneous rocks such as granite and its finer grained equivalents. This contrast has been interpreted by many 4 r 7~-'i ~ CITYOF ~ ~ COimEAUT ~ ~~ KINGSVILLE a.. l p. ~ £ / ASTABULA ~--. SAYBROOK v MONROE GENEVA SHEFFIELD PLYMOUTH WINDSOR ORWELL COLEBROOK WAYNE WILLIAMSFIELD < (.!:) w ~ l!--------~--------L-------~~-------L--------~ 1-­ < (.!:) 1-­ TRUMBULL COUNTY (/.) Figure 2. WELLS REACHING PRECAMBRIAN BASEMENT ROCK 5 geologists to be a structural feature known as the Grenville Front, named for exposures in Canada where metamorphic rocks of the Gren­ ville Geologic Province are in contact with older igneous rocks of the Superior Geologic Province to the west (ref. 5, p. 3) (fig. J). The Grenville Province is thought to underlie Ashtabula County and represent deeply eroded roots of a mountain range from a past orogenic event. In western Ohio, the Precambrian igneous rocks are a broad platform historically called the Cincinnati Arch. This could also be termed the Ohio-Indiana Platform (ref. 5, p. 4). Surrounding this platform are the Appalachian Basin to the east, the Michigan Basin to the north, and the Illinois Basin to the west. This Ohio-Indiana Platform may best be viewed as a relatively stable area, around which basinal areas have subsided, rather than an upwarped archlike structure. This area in which the Precambrian and overlying Paleozoic rocks dip away from this platform into the Appalachian Basin interestingly co­ incides with the proposed extension of the Grenville Front. This same area has also been described as a fracture rift zone of Keweenawan age. This postulated rift zone is said to have undergone periodic reactivation to recurrent crustal stresses. The July 27, 1980 northern Kentucky earthquake may suggest that movement is still occur­ ring along an ancient Precambrian zone of weakness. The importance of the Precambrian surface to the oil and gas in­ dustry is intriguing. If the ancient surface valley and ridges are dis­ covered, the draping of overlying Paleozoic sediments may have created traps for hydrocarbons. Also, if basement faults extend into the Paleo­ zoic, additional traps may occur. If periodic reactivation of a rift 6 I IWNOfS BASIN \. ..... r --. Figure 3. (Modified from Hansen, 1984o) 7 zone occurs and controls in part the pattern of deposition of Paleozoic sediments, stratigraphic traps may have occurred. With limited information on the Precambrian surface in Ashtabula County, additional information will need to be gathered for these above postulations to be helpful to the oil and gas industry. Although our knowledge of the Precambrian basement rocks has progressed greatly since Orton's time, the new questions that have arisen are possibly more confusing than enlightening. 8 THE CAMBRIAN PERIOD Early in the Paleozoic Era, the basins and arches that became prominent later in the Paleozoic were not sharply differentiated from the surrounding shelf (ref. 1). The Precambrian surface was exposed to erosional forces for an extensive period, before any deposition of Cambrian sediments. The Sauk transgressional sequence began in Pre­ cambrian time, and eventually covered the southern half of the craton in a great epeiric sea (fig. 4). The first sedimentary deposits were reworked sandstones that were left behind the advancing sea. In Ohio, this sand is called the Mt. Simon sandstone and is in general coarse to conglomeratic. The source of these sands was mainly granites of the Canadian Shield. These granites should have also produced enormous amounts of clay. Some geologists believe wind may have played an im­ portant role in removing this clay. Also, it may have been sifted from the sand by wave action. As the sea advanced northward through Ohio, in eastern Ohio the Rome formation was deposited. It consists first, in Ashtabula County, of siltstones and fine-grained sandstones. As the sea deepened, a thick layer of pelletal and oolitic dolomite was deposited, Overlying this dolomite deposit are shales with dolomitic fragments. In Ohio, this is termed the Conasauga Formation. Overlying the Conasauga in central Ohio is the Kerbel Formation. This is a fine-grained sandstone that coarsens upward. In the same stratigraphic position in northeastern Ohio is also a sandstone. This is not yet mapped as the Kerbel, but ultimately probably will be (ref. 7, p. 67). 9 CANADIAN \~SHIELD ...... '; I c-;::;---· I I ,._ ,.--------- . ~~ \ /, } ~ t ,/~ .----...._ __. .. ,., J• ; ' • ._ / \ ' -~ i '\ 'rr! ---·/}~-- \ ,, ~ I i I ,J;~/ 1 . """ ,- .. / -------- -, I ~~,.--: _,·--------- / II\__( _... / _/- ~ \ .....__ --------J __ .., _____ -........ .-' I : ~-- 1 I' ! .... --:-,;~:-- ----- / --·- ,-. I . .-· /' ·.) .... r ,:--· " I I I . \ !> ..* ....... - ... 1 ~------------------_.,....._.:,: _______________ _ 0 200ktr. t-1~ •.-·...., ...... ..,.._... :r--'' 0 Figure 4. (Modified from Hansen, 1984.) 10 No physical break marks the boundary between the Cambrian and Ordovician. Sandstones were still being deposited near the Shield's edge, while limestones accumulated over most of the southern and mar­ ginal parts of the continent. In Ohio, this formation is termed the Knox Dolomite. Within this dolomite, sandstone deposits are also found. This author chooses not to break this formation into subdivisions. Fossil evidence has not been obtained in the Appalachian Basin as far as is known. The Mt. Simon sandstone contains salt water in almost all wells drilled into this formation. The conclusion is that finding commercial hydrocarbons here is remote. This is also true for both the Rome and Conasauga Formations, unless the Rome Formation has local fracture por­ osity. The Kerbel Formation is considered potentially productive if it can be found structurally high and the overlying dolomite is impermeable (ref. 7, p. 67). Shows of gas in nearby Ohio counties of Stark, Mahoning, and Columbiana have been reported in the Kerbel. This author feels that the chances of commercial hydrocarbons being found in the Kerbel are minimal, but the sandstone should be checked in any deep test well. The highest potential for finding commercial hydrocarbons in the Cambrian would be in the Knox dolomite formation, with its sandstone lenses. As of February 1977, 17 wells had penetrated the Cambrian in Ashtabula County.